Vulnerability in Libssh2
CVE-2026-58051
libssh2 through 1.11.1 grows its publickey list with SSH2_REALLOC but does not zero-initialize new entries before parsing populates them, so a parse failure reaching the cleanup path leaves libssh2_publickey_list_free operating on an uninitialized entry. A malicious SSH server offering the publickey subsystem can use a malformed response to make cleanup free an uninitialized, attacker-influenceable attrs pointer in a connecting libssh2 client.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H.
EPSS exploit prediction
EPSS: 0.003 (18.0th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 18th percentile — 18.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: 0.000
Affected products
- Libssh2 — versions 0
Weakness classification (CWE)
References
- github.com/bikini/exploitarium/tree/main/libssh2-publickey-list-calc-poc (exploit, Broken Link, third-party-advisory)
- github.com/libssh2/libssh2/blob/master/src/publickey.c (Product, product)
- www.vulncheck.com/advisories/libssh2-free-of-uninitialized-pointer-in-publickey… (Third Party Advisory, third-party-advisory)
Frequently asked questions
- What is CVE-2026-58051?
- CVE-2026-58051 is a medium-severity vulnerability in Libssh2, classified under Use of Uninitialized Resource. CVSS score: 6.5/10. Published 2026-06-28.
- How severe is CVE-2026-58051?
- Medium severity. CVSS v3 base score is 6.5 out of 10.